The purpose of this study was to investigate the effects of the operating parameters. such as pH, initial concentration (C-i), duration of treatment (t), current density (j). interelectrode distance (d) and conductivity (K) on the treatment of a synthetic wastewater in the batch electrocoagulation (EC)-electroflotation (EF) process. The optimal operating conditions were determined and applied to a textile wastewater. Initially a batch-type EC-EF reactor was operated at various current densities ranging from 11.55 to 91.5 mA/cm(2) and various electrode gaps (1, 2 and 3 cm). For solutions with 300 mg/L of silica gel, good turbidity removal (89.6%) was obtained without any coagulant when the current density was 11.55 mA/cm(2), and with initial pH at 7.6, conductivity at 2.1 mS/cm: the treatment time was hold for 10 min and the electrode gap was 1 cm. Application of the optimal operating parameters on a textile wastewater showed a high removal efficiency for the following variables: suspended solid (SS) 85.5%, turbidity 76.2%, biological oxygen demand (BOD5) 88.9%, chemical oxygen demand (COD) 79.7%, and color over 93%. (C) 2009 Elsevier B.V. All rights reserved.